A precise measurement of the differential cross sections dσ/dω and the linearly polarized photon beam asymmetry ς3 for Compton scattering on the proton below pion threshold has been performed with a tagged photon beam and almost 4π detector at the Mainz Microtron. The incident photons were produced by the recently upgraded Glasgow-Mainz photon tagging facility and impinged on a cryogenic liquid hydrogen target, with the scattered photons detected in the Crystal Ball/TAPS setup. Using the highest statistics Compton scattering data ever measured on the proton along with two effective field theories (both covariant baryon and heavy-baryon) and one fixed-t dispersion relation model, constraining the fits with the Baldin sum rule, we have obtained the proton electric and magnetic polarizabilities with unprecedented precision: αE1=10.99±0.16±0.47±0.17±0.34, βM1=3.14±0.21±0.24±0.20±0.35; in units of 10-4 fm3 where the errors are statistical, systematic, spin polarizability dependent, and model dependent.
Measurement of Compton Scattering at MAMI for the Extraction of the Electric and Magnetic Polarizabilities of the Proton
Costanza, S.;Pedroni, P.;
2022-01-01
Abstract
A precise measurement of the differential cross sections dσ/dω and the linearly polarized photon beam asymmetry ς3 for Compton scattering on the proton below pion threshold has been performed with a tagged photon beam and almost 4π detector at the Mainz Microtron. The incident photons were produced by the recently upgraded Glasgow-Mainz photon tagging facility and impinged on a cryogenic liquid hydrogen target, with the scattered photons detected in the Crystal Ball/TAPS setup. Using the highest statistics Compton scattering data ever measured on the proton along with two effective field theories (both covariant baryon and heavy-baryon) and one fixed-t dispersion relation model, constraining the fits with the Baldin sum rule, we have obtained the proton electric and magnetic polarizabilities with unprecedented precision: αE1=10.99±0.16±0.47±0.17±0.34, βM1=3.14±0.21±0.24±0.20±0.35; in units of 10-4 fm3 where the errors are statistical, systematic, spin polarizability dependent, and model dependent.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
